Lithium secondary battery

EP4726836A4Pending Publication Date: 2026-06-24TERAWATT TECH KK
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Patent Information

Authority / Receiving Office
EP · EP
Patent Type
Applications
Current Assignee / Owner
TERAWATT TECH KK
Filing Date
2023-06-07
Publication Date
2026-06-24

AI Technical Summary

Technical Problem

Lithium secondary batteries using polyethylene terephthalate (PET) in current collectors experience performance deterioration due to chemical reactions with chain-like carbonates and/or chain-like ethers in the electrolyte solution, especially at high temperatures, particularly when nickel-containing positive-electrode active materials are used.

Method used

Incorporating a resin layer containing polyethylene terephthalate and a metal layer on both surfaces of the current collector, combined with an electrolyte solution containing vinylene carbonate and lithium difluorophosphate, suppresses chemical reactions and maintains battery performance at high temperatures.

Benefits of technology

The solution achieves high safety and excellent performance stability in lithium secondary batteries by preventing redox shuttle reactions and maintaining capacity retention rates even when stored at high temperatures.

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Abstract

The present invention provides a lithium secondary battery which is allowed to achieve both high safety and excellent performance stability at a high temperature. The present invention relates to a lithium secondary battery including a positive electrode that has a positive electrode current collector and a positive-electrode active material layer, a negative electrode that has a negative electrode current collector, an electrolyte solution, and a separator, in which the positive electrode current collector and / or the negative electrode current collector has a current collector film that includes a resin layer containing polyethylene terephthalate and a metal layer provided on each of both surfaces of the resin layer, the positive-electrode active material layer contains one or more compounds represented by a general formula: LizNixCoyM1-x-yO2+α (here, 0.5 ≤ x ≤ 1.0, 0 ≤ y ≤ 0.35, 0.9 ≤ z ≤ 1.3, - 0.2 ≤ α ≤ 0.15, and M is one or more elements selected from the group consisting of Mn, Al, V, Mg, Mo, Nb, Ti, Zr, Fe, Cu, Cr, Zn, F, and B), and the electrolyte solution contains a chain-like carbonate and / or a chain-like ether, vinylene carbonate, and lithium difluorophosphate.
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